Having no idea? Not like Sun solvers! (8)
I believe the answer is:
clueless
'having no idea?' is the definition.
(I've seen this before)
'not like sun solvers' is the wordplay.
I cannot really understand how this works, but
'not' could be 'less' (I've seen this in other clues) and 'less' is found within the answer.
The remaining letters 'clue' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for clueless that I've seen before include "How to describe difficult crossword" , "such a crossword can't be solved!" , "unlike this puzzle!" , "Stupid (so unable to do crossword?)" , "Knowing nothing" .)